Prev. Article Next Article Table of Contents

Communication

First-Principles Study of Aqueous Hydroxide Solutions

Bin Chen,*^† Jung Mee Park,^‡^§ Ivaylo Ivanov,^† Gloria Tabacchi,^‡^# Michael L. Klein,^† and Michele Parrinello^‡

Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany, Department of Chemistry, Division of Molecular and Life Sciences, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea, Centro Svizzero di Calcolo Scientifico (CSCS), via Cantonale, 6928 Manno, Switzerland, Physical Chemistry, ETH Zurich, Hönggerberg, 8093 Zurich, Switzerland

J. Am. Chem. Soc., 2002, 124 (29), pp 8534–8535

DOI: 10.1021/ja020350g

Publication Date (Web): June 26, 2002

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

†

University of Pennsylvania.

‡

Max-Planck-Institut für Festkörperforschung.

Pohang University of Science and Technology.

Present address: Dipartimento di Scienze Chimiche, Fisiche e Matematiche, Universitá dell'Insubria at Como, via Lucini 3, I-22100 Como, Italy.

⊥

Centro Svizzero di Calcolo Scientifico.

‖

ETH Zurich.

Abstract

Car−Parrinello molecular dynamics simulations have been carried out for aqueous NaOH and KOH solutions under ambient conditions over a wide range of concentrations. From these simulations, we have observed a continuous change of the water structure with added hydroxide, characterized by a significant shift of the second peak of the OO radial distribution functions to shorter distances. At the highest concentration investigated, the normal tetrahedral coordination of pure water is completely missing, a result that is consistent with a recent neutron diffraction experiment. The added hydroxide also gives rise to some unique spectroscopic features, including a “free” O−H stretch, a broadening of the normal water OH stretching band, and a large blue shift of both the librational band and the low-frequency translation. These results are in good agreement with the experimental data. Finally, it was demonstrated that the structural and dynamical behavior is inextricably linked to the formation of compact hydroxide−water complexes.

View: Full Text HTML | Hi-Res PDF